Sources of PM10 and PM2.5 in Cairo’s ambient air

A source attribution study was performed to assess the contributions of specific pollutant source types to the observed particulate matter (PM) levels in the greater Cairo Area using the chemical mass balance (CMB) receptor model. Three intensive ambient monitoring studies were carried out during the period of February 21–March 3, 1999, October 27–November 27, 1999, and June 8–June 26, 2002. PM₁₀, PM_2.5, and polycyclic aromatic hydrocarbons (PAHs) were measured on a 24-h basis at six sampling stations during each of the intensive periods. The six intensive measurement sites represented background levels, mobile source impacts, industrial impacts, and residential exposure. Major contributors to PM₁₀ included geological material, mobile source emissions, and open burning. PM_2.5 tended to be dominated by mobile source emissions, open burning, and secondary species. This paper presents the results of the PM₁₀ and PM_2.5, source contribution estimates.     

叶绿素a与环境因子关系的研究——以三明地区某水源地为例

根据2009～2012年水源地水质自动监测所得数据,分析叶绿素a的动态变化与环境因子的相关关系,筛选影响叶绿素a含量变化的环境因子。分析表明:该水源地水库水质状况属贫营养型,其中叶绿素a含量变化主要受总磷、水温、高锰酸盐指数影响,以这3种影响因子建立起的多元回归方程能较好的预测水库叶绿素a的变化趋势。     

Atmospheric carbonyls in a heavy ozone pollution episode at a metropolis in Southwest China: Characteristics, health risk assessment, sources analysis

Ambient carbonyls were continuously observed in the field during a heavy ozone pollution episode in Chengdu, China from August 4 to August 19, 2019, and the pollution characteristics, atmospheric photochemical reactivity, human health risk, and sources of carbonyls were analyzed. Fifteen carbonyls were quantified with average total mixing ratios of 20.38 ppbv Formaldehyde(9.86 ppbv), acetone(4.41 ppbv), and acetaldehyde(3.57 ppbv) were the three most abundant carbonyls. During the heavy ozone po...     

基于CFD模拟的不同尺度竖井模型内烟气温度分布相似性的研究

通过小尺寸实验来研究实际建筑结构的火蔓延和烟气控制是一种已经被验证的十分有效的方法。经典方法中尺寸缩放只需要保证Froude数不变即可。采用CFD模拟的方法研究由火灾引起的烟气羽流在高层建筑竖井内的温度分布情况,建立三种不同尺寸高层建筑竖井的相似模型,并对比模拟结果,得出了尺寸缩放的规律:在保证Froude数不变的前提下,还需保证竖井结构内的流动为湍流;同时得到了着火房间通风口无量纲面积大小和火源位置变化对不同尺寸模型内流动相似性效果的影响规律。     

Characterization of precipitation in the background of atmospheric pollutants reduction in Guilin: Temporal variation and source apportionment

Rainfall samples were collected from three observation sites in Guilin from 2013 to 2017, and the chemical composition characteristics of precipitation and the contribution made by different ion sources were analyzed when atmospheric pollutants levels were reduced. The results showed that acid gas emissions and atmospheric pollutant concentrations continued to decline during the study period. However, the change in the volume-weighted mean p H at the three sites suggested that acid rain pollutio...     

动态固相微萃取-气相色谱质谱法测定水中多种异味有机物

采用动态固相微萃取技术富集水样中2-异丙基-3-甲氧基吡嗪、2-异丁基-3-甲氧基吡嗪、2-MIB、β-环柠檬醛、2,4,6-三氯苯甲醚、GSM、α-紫罗酮和β-紫罗酮等8种异味有机物,并用气相色谱质谱法测定。通过优化试验条件,使方法在2. 00 ng/L～100 ng/L范围内线性良好,方法检出限为1. 0 ng/L～4. 4 ng/L。空白水样3个质量浓度水平的加标回收率为81. 0%～121%,6次测定结果的RSD为1. 7%～8. 9%。将该方法用于一水库实际水样的测定,结果 2-MIB、β-环柠檬醛、α-紫罗酮和β-紫罗酮检出,其余均为未检出。     

有机氯农药在岩溶区上覆土壤中的垂直迁移特征及对地下水的影响

选取典型表层岩溶泉域内的土壤剖面和表层岩溶泉水为研究对象,采用气相色谱(GC-μECD)对土壤和地下水中的有机氯农药(organochlorine pesticides,OCPs)进行定量分析,研究了有机氯农药在岩溶区上覆土壤中的垂直迁移以及对地下水的影响.结果表明,研究区所有土壤剖面中,HCHs和DDTs均有检出.HCHs和DDTs的含量范围分别为:0.77~18.3 ng·g-1(平均5.16 ng·g-1)和0.34~226 ng·g-1(平均16 ng·g-1).研究区土壤中的HCHs和DDTs峰值主要出现在土壤亚表层.在一年的观测期间,4个表层岩溶泉中均有HCHs和DDTs检出.泉水中HCHs和DDTs的含量范围分别为:2.09~60.1 ng·L-1(平均12 ng·L-1)和N.D~79.8 ng·L-1(平均9.16 ng·L-1).后沟泉、柏树湾泉、兰花沟泉的HCHs和DDTs含量以及水房泉中的HCHs含量均呈现出雨季高于旱季的特点.泉水中的HCHs、DDTs含量与泉域内土壤中的HCHs、DDTs含量并没有很好的对应关系.研究表明,TOC、土壤含水量、黏粒含量、p H均对后沟泉域土壤中有机氯农药垂直迁移产生抑制作用,致使后沟泉域土壤中有机氯农药含量虽然在4个泉域中最高,但泉水中的含量却最低.而在水房泉泉域,这4个因素对有机氯农药的垂直迁移均没有抑制作用,因此水房泉泉域土壤中有机氯农药含量虽然最低,但泉水中有机氯农药的含量却较高.     

Formation mechanisms of nitrous acid (HONO) during the haze and non-haze periods in Beijing, China

As an important precursor of hydroxyl radical (OH), nitrous acid (HONO) plays a significant role in atmospheric chemistry. Here, an observation of HONO and relevant air pollutants in an urban site of Beijing from 14 to 28 April, 2017 was performed. Two distinct peaks of HONO concentrations occurred during the observation. In contrast, the concentration of particulate matter in the first period (period Ⅰ) was significantly higher than that in the second period (period Ⅱ). Comparing to HONO sources in the two periods, we found that the direct vehicle emission was an essential source of the ambient HONO during both periods at night, especially in period Ⅱ. The heterogeneous reaction of NO₂ was the dominant source in period Ⅰ, while the homogeneous reaction of NO with OH was more critical source at night in period Ⅱ. In the daytime, the heterogeneous reaction of NO₂ was a significant source and was confirmed by the good correlation coefficients (R²) between the unknown sources (P_unknown) with NO₂, PM_2.5, NO₂ × PM_2.5 in period Ⅰ. Moreover, when solar radiation and OH radicals were considered to explore unknown sources in the daytime, the enhanced correlation of P_unknown with photolysis rate of NO₂ and OH ($J_{{\mathrm{NO}}_2}$ × OH) were 0.93 in period Ⅰ, 0.95 in period Ⅱ. These excellent correlation coefficients suggested that the unknown sources released HONO highly related to the solar radiation and the variation of OH radicals.     

An improved grey wolf optimizer algorithm for identification and location of gas emission

Identification of the leakage of hazardous gases plays an important role in the environment protection, human health and safety of industry production. However, lots of current optimization algorithms, such as particle swarm optimization (PSO) and Grey Wolf Optimizer (GWO), suffer from poor global optimization capability and estimation accuracy. In this work, a hybrid differential evolutionary and GWO (DE-GWO) algorithm is proposed. Tested by simulation cases and Prairie Grass emission experimental data, DE-GWO shows higher estimation accuracy than GWO. Compared with the other four optimization algorithms, DE-GWO exhibits finer robust stability under different population sizes, fewer iterations, as well as higher estimation accuracy with fewer search agents. Importantly, simulation results demonstrate that DE-GWO is more suitable to apply in the scene with a small number of sensors. Therefore, the proposed in this paper outperforms other optimization algorithms for the gas emission inverse problem. DE-GWO can provide reliable estimation towards gas emission identification and positioning, which shows huge potential as the data analysis module of real-time monitoring and early warning system.     

2016-2020年珠海市金湾区集中式饮用水水源地环境质量变化特征

根据2016-2020年珠海市金湾区集中式饮用水水源地的监测数据,采用单因子评价法、综合污染指数法和综合营养状态指数法对金湾区黄绿背水库、爱国水库和木头冲水库环境质量变化趋势及特征进行分析评价.结果表明,2016年3个水库的综合污染指数最高,水质最差,超标因子为总磷,除了 2016年黄绿背水库超出《地表水环境质量标准》...